A conventional umbrella as shown in FIG. 1 includes: a top rib T pivotally secured to an upper notch N formed on an upper end of a shaft F and a stretcher rib S pivotally secured between the top rib T and a runner R slidably held on the shaft F, in which the rib T may be easily bent downwardly or upwardly if subjected to a strong wind pressure or an external force, thereby breaking or deforming the rib, especially harmful for a larger umbrella used in a beach, a golf course or a storming weather areas.
For reinforcing the rib assembly of another conventional umbrella as shown in FIG. 2, the top rib T may be made with double beams as shown in FIG. 2a to greatly increase its strength for overcoming a strong wind pressure or external force. However, the double-beam rib may greatly increase the weight of an umbrella and increase the production complexity and cost of an umbrella.
The present inventor has found the drawbacks of such conventional umbrellas and invented the present umbrella with simply reinforced top ribs in a rib assembly of the umbrella.